This is a total nuance feature, but I just thought I'd throw it out
anyways because it's one of those features that makes usage really
slick:

One thing I like to do is skip forward through a playlist while I'm on
shuffle to find a track I like. It seems like the lag between tracks is
from the loading of the next track from the HD. Has anyone thought of
loading the first 5 seconds of the track following the next track such
that if you hit forward again, it already has the next track loaded.

In essence, it's always loading up a little of the next track such that
it already has it loaded and can start playback immediatly, while
loading up the next track (just in case the skip button is hit again).
Then, if the user decides to continue playback, it just discards that 5
seconds of the next track and continues playback like normal.